As far as Planeswalkers go, Ajani is a great place to start for any player, giving their creatures more power, and the option to overwhelm an opponent in an instant
If I've got Elrond and Herd Baloth on the field and cast the Cryptic Annelid I showed you earlier, I'll pay four mana, scry 1, scry 2, scry 3 and end up with an additional 17 power on board in the form of three 4/4 beast tokens, a 1 power Cryptic Annelid and six +1/+1 counters
This set is actually pretty good in terms of playability, especially Coalossal VMAX and Donphan/Phanpy
It also works well in aristocrat strategies that can sacrifice the Warden and recur it to get continual value
4 mana for this effect is way too little in any reasonable format
Throw this on some of the new, nasty creatures that punish them for blocking like Phyrexian Vindicator or, its scarier and much more blockable friend, "Phyrexian Vindicator with a Colossus Hammer"