You have the option to use the following sizes which are A6 (4 by 6 ), 4-Bar ( 3 by 5) the smallest size for cards, A2 (2 by 6), A7 (5 by 7), A8 (5 by 8), A8 Slim (5 by 8), A9 (5 by 8 ) and Square (6 by 6 )
For seven mana, you get a Sorcery that makes every player sacrifice every colored permanent they control
Getting three mana of one color is pretty hard in Limited, and isnt even guaranteed by turn 6 in most decks
Straight out of the gate, Unrivaled Lethality doubles all damage that this card deals (and that can stack with double strike), not just combat damage, making it actually more like a 4/2 for three mana, but thanks to its next ability to easily get more counters when it deals damage to another creature which can quickly make this card a powerhouse
This card works really well with other spectacle cards or any card that has a triggered ability when your opponent loses life such as Savage Gorger or Arrogant Outlaw
If heads, during your opponent's next turn, prevent all effects of attacks, including damage, done to Seadra