- When using this card, the most important thing to remember is that it doesn't gain any Power on its own upon Superior Riding it and it's base 10000 Power will struggle against 11000 Power Vanguards. Methods so solve this include:
- Do not boost your Vanguard's first attack so the rear-guard behind it can boost Dark Rex. Vanguards that can power themselves up like Tyrant, Deathrex, orStrides that can already attack for at least 25000 on their own are the best candidates, additionally you can use Dark Rex's second effect to power up the first Vanguard.
- Retire cards like Winged Dragon, Beamptero or Coelamagnum as cost for Dark Rex's Limit Break then use their effects to Power up Dark Rex.
- Destruction Tyrant, Fullblade Rex and Baby Camara can call a Grade 1 behind your Vanguard after your first Vanguard attack.
- Superior Ride Dark Rex over Ancient Dragon, Spinodriver and use it's Break Ride effect. Do note that you can't Stride the turn you do this.
- If your opponent has 3 damage or less they'll be unlikely to guard your Vanguard and let you use Dark Rex, so you can use a G-Unit or a Critical gainer Grade 3 to pressure the opponent into either guarding your Vanguard's attack or push them to 5 damage and force them to guard your next turn.
- When your opponent is at 4 damage they may be tempted to let your Vanguard's attack hit so you can't Superior Ride Dark Rex, giving you a chance to win if you check a Critical Trigger
- G-Units' Triple Drive makes it easier to check triggers in this case.
- Use Vanguards that gain criticals by themselves to apply this pressure when the opponent has lower damage.
- Use Explosive Dragon, Sarcoblaze to pressure the opponent into not using their Perfect Guards and likely force them to let your Vanguard hit or use too many shield to guard it if they don't want to risk a Critical Trigger.
- Use Destruction Tyrant, Hellrex Maxima or Rupture Dragon, Minirex to bind this card directly from your deck.
- Even if you don't get to Superior Ride Dark Rex that turn, it'll stay in the Bind Zone to use it a later turn.
- Notable rearguards you can retire with this card's Limit Break include:
- Dragon Egg and Assault Dragon, Blightops: Get a 10000 Shield card to defend with.
- Winged Dragon, Skyptero: Recover it to call it to boost again next turn or use it as cost for a Perfect Guard.
- Winged Dragon, Beamptero and Winged Dragon, Slashptero: Increase this card's power after superior riding it.
- Baby Camara: Call a Grade 1 behind Dark Rex and boost it. Sonic Noa is a good choice as it'll boost Dark Rex to 21000 Power.
- Tank Mammoth: Do an additional 11000 Power attack, have a standing rear-guard to give Trigger effects to, then you can retire it to call a Destruction Dragon, Squallrex after Dark Rex attacks.
- Coelamagnum and Assault Dragon, Assaultrex: Recover hand advantage without spending Counterblasts.
- When using this card's secondary ability, you can apply the power increase to a Raging Dragon, Blastsaurus to grant it enough power to beat a Vanguard without boosting the Unit with the Rear-Guard. Then, when Raging Dragon, Blastsaurus is replaced by its effect with a new version of it, you can still use the boosting Rear-Guard on the second Raging Dragon, Blastsaurus. This can be very useful if you don't have Raging Dragon, Sparksaurus.
- Use Military Dragon, Raptor Colonel and the Brachio series to attack a vast number of times in the same turn.
- Citadel Dragon, Brachiocastle boosted with Transport Dragon, Brachioporter, then attack with a Tachikaze boosted with another Brachioporter.
- With a Brachiocastle in the back row rear-guard, finally attack with Military Dragon, Raptor Colonel and use its Limit Break to retire the Brachiocastle and Brachioporter column. Use each unit's counterblast to call Carrier Dragon, Brachiocarrier to the front row rear-guard and another Brachioporter behind it.
- If the attack is guarded, use this card's Limit Break to retire the Brachiocastle, the Tachikaze in front row rear-guard, and the resting Brachioporter, and use the Brachioporter's counterblast to call another Brachiocarrier to the front row rear-guard and the Brachiocastle's counterblast to call another Brachioporter behind this card
- Attack with Brachiocarrier boosted with the Brachioporter then attack with this card boosted with another Brachioporter (it is best to use any triggers on the remaining Brachiocarrier otherwise it will most likely lack the attack power to damage the enemy vanguard) finally attack with the remaining Brachiocarrier, giving you a total of 6 attacks at the cost of 5 counterblasts.
- When you already have a Dark Rex in Vanguard, use Tank Mammoth and Rain Element, Madew to make a loop to keep using Dark Rex's effect every turn:
- Superior Ride a second copy of Dark Rex retiring Tank Mammoth as part of the cost.
- Use Tank Mammoth's cost to Soulblast the first Dark Rex.
- On your next turn Stride Madew and recover the Dark Rex you soulblasted, and repeat the process.
Countering
- It's very easy to predict when you're opponent is planning to use Dark Rex given that it needs to be in the Bind Zone beforehand, so as soon as your opponent binds it start preparing for it.
- It is risky, but you can no guard your opponent's Vanguard's attack if you're at 4 damage. If your opponent's Vanguard hits the turn they were planning to use Dark Rex. their strategy for that turn will most likely be messed up.
- Keep in mind your opponent can potentially check a Critical Trigger (and they have more chance to do so if they Stride) so think VERY carefully before deciding to guard or not, perhaps ask to check your opponent's playing field to count how Many Critical Triggers are outside the deck.
- If your Vanguard's Power increases (via triggers or effects like Black Shiver, Gavrail), Dark Rex's attack becomes significantly less threatening because it is a base 10000 card that doesn't gain Power on it's own.