This card cannot be called as a copy of Outbreak. It has a different mechanic with one of the effects but exactly the same conceptual idea (due to art,name,theme) which is an ignored factor when an identity crisis arise.
For telling whether Pestilence is a worthy stand alone card separate from Outbreak, we will split both cards into the two effects they both have :
Effects | Pestilence | Outbreak | Verdict |
Part 1 | Poisons the creature each turn.Cumulative. | Infect the creature by 1 poison. | Different mechanism. |
Part 2 | Jumps to a random creature upon death. | Jumps to 2 random creatures upon death. | Same mechanism, only number difference. |
I agree even in mechanism there is similarity but you cannot call it as identical copy of Outbreak because Pestilence has it's own different mechanism which is more original to the game than Outbreak. Infect already exists in Parasites, Plagues and Retrovirus but i never heard of cumulative poison stacking on a creature before.
In game it can be used to kill those high hp creatures faster. Although expensive and affects one creature at a time, it doesn't seem to have any effective counters. Excellent synergy with Death.
Suggestion : To remove the similarity of the second effect, change it to " Jumps to a nearby creature " which gives a dual benefit - removing similarity with Outbreak and granting some gameplay bonuses giving more control to the caster to which creatures get affected. This allows you to choose whether enemy or friendly creatures are to be killed by choosing fields. This would be a strong combo in a flooding water/death death deck where you control the opponents creatures in top and bottom row, trapping them and while they are infected inside with Pestilence. Another fun part could be that a creature in top row in your field can transfer poison to creatures in opponent's bottom row.
Overall, a well thought out card on it's own. (By trusting that you thought out the idea yourself)