Druid's Familiar

Soulbond's anthem variant, and the one that exposes how the keyword actually distributes power. The +2/+2 here is reciprocal: pair this with any unpaired creature and both bodies grow, which means the card is buffing itself the moment it finds a partner as much as it is buffing whatever it locks onto. Pair it with a one-drop and you have turned that one-drop into a credible threat while the Bear stands as a 4/4 of its own. Pair two copies together and the static abilities stack, since each grants +2/+2 to both paired creatures, so the partnership carries +4/+4 across it and you have two 6/6s. The keyword's restriction is what keeps the math honest: the bonus persists only as long as you control both paired creatures, so removal on one drops the survivor back to its own base stats (the Familiar to a 2/2). That fragility is the load-bearing element. A flat four-mana anthem would be safe and dull; tying the buff to a partner you must also protect makes the card a two-for-one waiting to happen, and the payoff is priced to match that exposure. It rewards a board with another creature already in play, since soulbond needs an unpaired partner to attach to. Played onto an empty board it cannot pair with anything, so its static ability lies dormant and it is only a 2/2 body until a teammate arrives to complete the bond.